The cooling method used in a conventional plastic grains making machine exposes the plastic grains to air for cooling. However, when the plastic grains are discharged from the machine, they are very hot and can not be easily cooled within a short period of time by the air cooling method. Thus, the plastic grains so produced may adhered together into a mass. With plastic materials of high viscosity, the situation is worse, and the plastic materials so produced may not be able to form into grains. Therefore, the method of self cooling in air can not provide a sufficient cooling effect, and more, particularly, in high speed methods, the quality is difficult to control. In order to provide a better cooling effect, an improved water cooling system is adopted currently. The present invention uses a water cooling system in plastic grains making, which provides the following features:
1. By means of cutter blades, plastic materials are cut into grains and the grains are pushed to the inner wall to mix with a whirlpooling column of cooling water, in order to increase the cooling surface of the grains with the cooling water so as to provide a quick and complete cooling effect.
2. The cutter blades are arranged around the circumference of a revolving plate, so that when the plastic materials pass through escape holes in the mold, they are quickly cut into grains by means of the rotation of the revolving plate which increases productivity with improved quality.
3. The plastic grains are fully mixed with the whirlpooling column of cooling water to speed up the cooling effect and are washed out through a drain hole together with the cooling water to prevent any sticking of grains.